Method and apparatus for triggering radio link control packet discard and radio link control re-establishment

Abstract

A method and apparatus for triggering radio link control (RLC) re-establishment and/or protocol data unit (PDU) discard are disclosed. An RLC entity maintains a state variable for counting a total number of transmissions and/or retransmissions of an RLC PDU and its PDU segments. If the state variable reaches a threshold, the RLC entity initiates RLC re-establishment and/or discards the RLC PDU and PDU segments. The state variable may be incremented each time a negative acknowledgement is received for at least a portion of the RLC PDU or when a retransmission is considered for the RLC PDU or a portion of the RLC PDU. The RLC entity may increase a state variable proportionate to a retransmitted data size. The RLC entity may maintain separate state variables for the RLC PDU and PDU segments and counts the number of transmissions and/or retransmissions for the RLC PDU and the PDU segments.

What is claimed is: 
     
       1. A method for triggering radio link control (RLC) re-establishment, the method comprising:
 transmitting an RLC protocol data unit (PDU) for a first time as a first transmission; 
 initializing a state variable to zero on a condition that the RLC PDU is considered for retransmission for a first time as a first retransmission following the first transmission; 
 incrementing the state variable associated with the RLC PDU on a condition that at least a portion of the RLC PDU is considered for retransmission as a subsequent retransmission subsequent to the first retransmission; and 
 initiating RLC re-establishment based on a threshold test of the state variable. 
 
     
     
       2. The method of  claim 1  wherein the state variable is not incremented on a condition that the at least a portion of the RLC PDU considered for retransmission is already in a retransmission buffer. 
     
     
       3. The method of  claim 1  further comprising:
 discarding an RLC service data unit (SDU) at least a portion of which is contained in the RLC PDU; and 
 discarding an RLC PDU and a PDU segment that contain at least a portion of the discarded RLC SDU. 
 
     
     
       4. The method of  claim 1  further comprising:
 performing a move receive window (MRW) procedure. 
 
     
     
       5. The method of  claim 1  further comprising:
 discarding at least one of the RLC PDU and segments of the RLC PDU. 
 
     
     
       6. An apparatus configured to trigger radio link control (RLC) re-establishment, the apparatus comprising:
 a transmitter configured to transmit an RLC protocol data unit (PDU) for a first time as a first transmission; and 
 an RLC entity configured to set a state variable to zero on a condition that the RLC PDU is considered for retransmission for a first time as a first retransmission following the first transmission; 
 the RLC entity further configured to increment the state variable associated with the RLC PDU on a condition that at least a portion of the RLC PDU is considered for retransmission as a subsequent retransmission subsequent to the first retransmission; 
 the RLC entity further configured to initiate RLC re-establishment based on a threshold test of the state variable. 
 
     
     
       7. The apparatus of  claim 6  wherein the RLC entity is configured to not increment the state variable on a condition that the at least a portion of the RLC PDU considered for retransmission is already in a retransmission buffer. 
     
     
       8. The apparatus of  claim 6  wherein the RLC entity is further configured to discard an RLC service data unit (SDU) at least a portion of which is contained in the RLC PDU and discard an RLC PDU and a PDU segment that contains at least a portion of the discarded RLC SDU. 
     
     
       9. The apparatus of  claim 6  wherein the RLC entity is further configured to perform a move receive window (MRW) procedure. 
     
     
       10. The apparatus of  claim 6  wherein the RLC entity is further configured to discard at least one of the RLC PDU and segments of the RLC PDU.